1. Field of the Invention
This invention relates to a treatment for ripening of the cervix, particularly in the induction of labour to assist mammals to give birth.
2. Description of the Related Art
Parturition (expulsion of the fetus from the uterus), requires both contractions of the myometrium, the smooth muscle of the uterus, and a softening of the highly connective tissue of the cervix, so that it will stretch and dilate sufficiently to allow the fetus to be expelled. This softening is known as "ripening".
The current preferred method of cervical ripening is by the use of prostaglandin E2. This is used as a vaginal gel or tablet or as a gel placed in the cervix. One worry about the use of PGE.sub.2 is that there is a possibility of hyper-stimulation of the uterus, leading to myometrial contractions before the cervix is ripened and therefore before a comfortable or safe birth is possible. The ideal preparation would soften and efface the cervix without causing myometrial contractions. This would allow the subsequent contractions (inducible if necessary with a small dose of prostaglandin) to deliver the baby with a minimum of resistance.
There is good evidence from animal experiments that the antiprogestins such as RU486 would meet these requirements, but the problem with this drug is that it has associated antiglucocorticoid activity leading to elevated cortisol and ACTH levels X. Bertagna et al. J Clin Endocrinol Metab 78, 375-380 (1994)! and might also be detrimental to the fetus.
The use of interleukin-8 has also been proposed previously as an agent to ripen the cervix (WO 93/09796). It is known that IL-8 production is suppressed by progesterone R W Kelly et al, The Lancet, 339, 776-777 (1992); R W Kelly et al. Human reproduction 9, 253-258 (1994)!.